When external light such as sunlight or indoor illumination light reflects on a screen of a display device, contrast of the screen lowers, the screen becomes white and it becomes hard to view an image. In order to prevent such a phenomenon, an anti-reflection film has been conventionally proposed which is adhered to a surface of a display device and prevents reflection of external light.
Such an anti-reflection film is disclosed in, for example, Japanese Published Unexamined Patent Application No. 2002-122702 (Patent Document 1). The anti-reflection film is formed in a manner of bringing projections (protrusions), each which has a refractive index equivalent to that of a transparent film substrate, into close formation on a surface of the film substrate. The projection has a triangular cross section, that is, is in the shape of a pyramid (four-sided pyramid) or cone.
Such an anti-reflection film is sometimes provided, for use, on a surface of an outer face of equipment, for example, a surface of a transparent protective plate of a display device. When a surface of the anti-reflection film is rubbed with a soft cloth or cleaner to wipe sebaceous matter, dirt deposited on the surface of the anti-reflection film, the pyramid-shaped or conic projections are easily worn down and crushed, and an anti-reflection function of the anti-reflection film is easily impaired. Similarly, when the transparent protective plate is strongly pushed by a finger, the projections on the surface are crushed and the anti-reflection function is easily impaired.
Additionally, in the display device or the like, the anti-reflection film is sometimes adhered to a back face of the transparent protective plate or a display element under the back face. Also in this case, when the transparent protective plate is pushed by a finger or a touch pad pen, the transparent protective plate comes into contact with the display element, and thus, in some cases, the projections of the anti-reflection film are crushed by pressure, and the anti-reflection function of the anti-reflection film is lowered and impaired.
In order to solve the problems, in an anti-reflection film disclosed in Japanese Published Unexamined Patent Application No. 2004-70164 (Patent Document 2), nano-order projections are closely formed and micron-order protection poles higher than the height of the projections are scattered on a surface of the anti-reflection film. The protection poles protect the projections and prevent the projections from being damaged when the anti-reflection film is rubbed or pushed.
However, in the case where the anti-reflection film having such protection poles is provided on a surface of equipment, when the anti-reflection film is wiped with a soft cloth, feathered cloth or the like, the cloth or the like passes over the protection poles and comes into contact with the projections of the anti-reflection film, and the projections are destroyed. Additionally, also in the case where the anti-reflection film is provided on an inner face of a display device or the like, there is a possibility that the protection poles are damaged depending on the height of the protection poles or in the method of applying force.
Additionally, in the anti-reflection film disclosed in Patent Document 2, a reflectance of light becomes large owing to the protection poles thereby impairing a low reflectance property of the anti-reflection film, and a haze value becomes large owing to the protection poles thereby making an optical property poor. Additionally, in the case where the anti-reflection film having the micron-order protection poles thereon is used for a high-definition display device, the protection poles are viewed through a screen thereby causing a defect on an image.    [Patent Document 1] Japanese Published Unexamined Patent Application No. 2002-122702    [Patent Document 2] Japanese Published Unexamined Patent Application No. 2004-70164